Sawing and chipping machine

ABSTRACT

A sawing and chipping machine for providing a sawn face on a log having a rotable head on which a circular saw and chipping knives are mounted for sawing a slab from a moving log and at the same time reducing the slab to chips suitable for pulping.

[451 Dec. 25, 1973 United States Patent 1191 Chapman [541 SAWING AND CHIPPING MACHINE [5 6] References Cited UNITED STATES PATENTS Inventor: Frederic Frank Chapman,

Coquitlam, British Columbia, Canada Segal......

Primary Examiner-Donald R. Schran AttorneyBrian .1. Wood Appl. No.: 238,115

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[51] Int. [58] Field of Search.................. 144/39, 162R, 176,

144/223, 3 P, 3 R; 241/293; 83/848 7 Claims, 10 Drawing Figures LATENTEU DEC 25 1975 SHEET 1 BF 3 JATENTEU [15025 I975 3.780.778

SHEET 2 [1F 3 SAWING AND CHIPPING MACHINE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to machines for sawing and chipping logs and in particular to chipping and sawing head assemblies for such machines.

2. Prior Art In production of lumber from logs it is common practice to chip, rather than to saw, the log to a dimension suitable for further reduction to dimensioned lumber. Chips can, advantageously, be used in pulping operations and kerf loss, normally associated with a sawing operation, is eliminated in chipping.

In some applications, however, it is necessary to provide a sawn rather than a chipped face. Although machines have been developed which automatically saw slabs from the log and then convert the slabs to chips, kerf loss is still a problem in these machines.

SUMMARY OF THE INVENTION The present invention provides a sawing and chipping machine in which kerf loss is materially less than in prior art machines known to the present inventor.

A machine according to the invention includes a I combined sawing and chipping head assembly which commences sawing ofa slab from a log to provide a flat sawn face and, at the same time, reduces the slab being cut to wood chips suitable for use in pulping.

In one embodiment of the present invention the head assembly includes a head rotatable about an axis perpendicular to the log, the head having a circular saw mounted thereon. The saw is segmented having individual, circumferentially extending, segments which are spaced apart to provide gaps for chipping knives which project between adjacent spaced saw segments. As the saw cuts the log to produce a sawn face, the chipping knives progressively reduce to chips the slab being cut.

Radius of each saw tooth of each segment is greater than that of a preceeding tooth by a distance such that extra load which, otherwise, would be applied to a tooth following a gap, is distributed essentially uniformly to each tooth of the segment. That is to say, the saw segments are eccentric with respect to the axis of rotation of the head.

In another embodiment of the machine the saw rather than having conventional saw teeth has chipping teeth which chip a kerf and which are dimensioned and spaced so that wood chips meet minimum dimension standards for pulping chips.

A detailed description following, related to drawings, gives exemplification of a machine according to the invention which, however, is capable of expression in means other than those particularly described and illustrated.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective of one embodiment of a sawing and chipping machine according to the invention,

FIG. 2 is an enlarged fragmented isometric projection of a portion of a head assembly,

FIG. 2A is a perspective of a portion of a log showing detail of cut,

FIG. 3 is an elevation of a head assembly showing relative positions of saw segments and chipping knives,

FIG. 4 is a fragmented partly sectioned detail showing a portion of a saw segment,

FIG. 5 is a section on 5-5 of FIG. 4,

FIG. 6 is a fragmented detail section of a saw segment, and a chipping knife shown in broken outline, illustrating relationship of cuts taken during operation,

FIG. 7 is a perspective view showing partially, an alternate form of a head assembly,

FIG. 8 is an enlarged side view ofa chipping tooth of the head assembly of FIG. 7,

FIG. 9 is a section on 99 of FIG. 8 showing the relationship of cuts taken by the chipping tooth and a chipping knife.

DETAILED DESCRIPTION FIGS. 1 and 3 FIG. 1 shows one embodiment of a sawing and chipping machine, generally 10, sawing and chipping a log 11 to provide a timber having opposite sawn side surfaces l212 and upper and lower chipped surfaces l313. The machine has a frame 14, and a pair of axially aligned chipping head assemblies 16 and 17 which are spaced as shown on a common horizontal drive shaft 18, having a rotational axis 18.1, the drive shaft being driven in a direction, arrow 19, by an electric motor 20.

Feed rollers 21, driven by an electric motor 21.1, feed the log between the head assemblies in a direction, arrow 21.2, at right angles to the axis 18.1 of the drive shaft 18.

The head assembly 16 has a head 22 having a face 23 confronting the log. A segmented circular saw 24 having three saw segments 24.1, 24.2, 24.3 see FIG. 3, is mounted on the face 23 of the head, the saw segments having teeth, severally 25, which project outwards of a periphery of the head and have inner faces, severally 26, which lie in a common plane confronting the log 11. Machine screws 27, see FIG. 2, which secure the saw segments to the head are counter sunk so that heads of the screws are inwards of the faces 26 of the segments.

FIGS. 2 and 2A Chipping knives, severally 31 are bolted to projections 32 on the chipping head, a chipping knife being located between adjacent pairs of saw segments and being sited relative to the saw segments, as hereafter to be described, so that, see FIG. 2 they progressively chip away a slab being cut from the log by the saw as the log is fed through the machine providing a chipped end face 33 on the slab.

FIGS. 2, 3, 4, and 5 The saw segments 24.1, 24.2, 24.3, see FIG. 3, are the same, consequently only saw segment 24.1 is fully illustrated and described.

The saw segment 24.1, see FIGS. 2, 4, and 5, has a thick inner portion 35 (FIG. 1) from which the teeth 25 project. Ratio of thickness of saw tooth and inner portion 35 is not fixed. Optimum thickness ratio is dependent on saw tooth length. The saw teeth are spaced apart conventionally to provide gullets 36 which have rounded bottoms 37, see FIG. 4, bevelled away from the face 26 as seen at 37.1.

FIG. 3

FIG. 3 shows, diagrammatically, disposition of the saw segments 24.1, 24.2, and 24.3 on the head 16.

As illustrated, leading and following ends 38 and 39 of the segment 24.1 are cut back as are the leading and following ends of the other segments, to provide gaps, severally 41, to accommodate the knives, two knives only being shown. The gaps, as illustrated, are about five saw teeth in extent.

The segment 24.1 is a segment of a circular saw, tooth tips of which describe a circle 42 having a radius 42.1 and a center 43.

It is seen that if the segments were to be positioned with the center 43 on the axis 18.1 of the head, the circle 42 described by the teeth tips would be concentric about the axis 18.1. Consequently, the lead tooth of the segment would be overloaded to an extent equal to the out which would be normally taken by saw teeth missing by reason of the gap preceeding the lead tooth. The lead tooth of the segment would, consequently, wear faster than the teeth following.

To obtain essentially uniform loading of each tooth in the segment the segment is located so that the center 43 is eccentric to the axis 18.1 of the head, with the trailing tooth 25.2 of the segment lying on the circle 42 and with the lead tooth 25.1 of the segment radially inset from the circle 42 a distance c such that where:

a is distance between the trailing tooth of one segment and the lead tooth of a following segment, 12 is distance between tips of adjacent teeth, c is radial inset of the lead tooth of each segment from the circle 42,

d is normal tooth bite of a circular saw having radius and tooth spacing equal to radius and tooth spacing of the segment.

Thus the extra load on each segment is distributed essentially uniformly to each tooth of the segment, and the saw teeth tend to wear uniformly.

FIGS. 2 and 6 As seen in FIG. 2 in which one chipping knife is shown, the knife is trapezoidal havinga bevelled cutting edge 47 which slopes inwards to flat inner end face 48. The knife is mounted so that the face 48 lies in a plane parallel to the face 26 of the segment and, see FlG. 6, extends into the kerf cut by the saw teeth but terminates short of the inner face 26 of the segment so as to provide a clearance 49 with the sawn surface 12 of the log.

As the head rotates depth of kerf is at a maximum following the trailing tooth of each segment and is at a minimum after the chipping knife following makes its cut. Difference 50, see FIG. 6, between maximum and minim um depths of kerf is a function of relationship of rate of feed of the log and rotational speed of the head, fora head having a given number of knives. This relationship, which also governs segment off-set to obtain uniform loading of the saw teeth of each segment, is such as to provide chips of required thickness for pulping, so that the difference 50 between maximum and minimum kerf depth is not greater than desired chip thickness.

The radial length of the trailing tooth of each segment is greater than the radial length of the chipping knife following so that cuts taken by the chipping knives are clear of the kerf bottom, leaving a lip 51. Thus as the kerf bottom always precedes the cuts taken by the knives, a sawn surface is always provided on the log.

Tooth configuration of the saw segments is such that gullet length is always greater than maximum kerf depth so that the gullet bottoms are always open i.e. clear of the slab.

The head assembly 17 is the same as the head assembly 16 consequently further description of the assembly 17 is deemed unnecessary. Further, as described previously, although the upper and lower surfaces 13 are chipped rotatable chippers, not shown, being incorporated in the machine immediately following the heads 16 and 17 it is to be understood that if four sawn sides are required head assemblies corresponding to head assemblies 16 and 17 and rotatable about an axis at right angles to the axis of the drive shaft 18 can be incorporated in the machine either to follow or to precede the head assemblies 16 and 17.

OPERATION When the log is fed between the head assemblies the saws produce the sawn surfaces 12-12, see FIGS. 2A, while the chipping knives chip away a slab being cut. As bottoms of the gullets are always open, sawdust produced by the teeth, as they progressively cut, is moved inward into the gullet and discharged laterally outwards by the bevelled gullet bottoms. Gullet length can therefore be considerably less than gullet length of conventional circular saws as sawdust storage space, normally provided by the gullets of conventional saws, is not necessary.

In all'circular saws blade thickness must be less than kerf width so as to obtain clearance between the sides of the saw and walls of the kerf. In large diameter conventional circular saws saw blade thickness, in order to obtain sufficient rigidity, results in material loss of wood due to kerf.

in the machine 10 blade rigidity is obtained mainly by reason of the thick inner portion, and also due to the fact that the segments are fixed to the head. Tooth length of the saw segments can be materially less than tooth length of conventional circular saws for adequate tooth rigidity, hence thickness of the teeth can be materially less than blade thickness of conventional saws, thus materially reducing width of kerf and kerf loss. FIGS. 7, 8 and 9 FIGS. 7, 8, and 9 show an alternate form of chipping head assembly, generally 60, which can replace either or both of the chipping head assemblies 16 and 17.

As seen in FIG. 7 the head assembly 60 has a head 61 mounted on a drive shaft 62 and having chipping knives, severally 63, which are equidistantly spaced apart as described with reference to the chipping knives of embodiment 10. Curved segments 64, 65, and 66 which are similar to, and have the same thickness as, the saw segments of the head assembly 16 of the machine 10 are fastened to the head 61 by countersunk machine screws, severally 67.

The segments 64, 6S, and 66, unlike the saw segments 24.1, 24.2, and 24.3 of the machine 10 do not have saw teeth, but have radially extending, equidistantly spaced chipping teeth, severally 68. Typically, three chipping teeth, having the same cutting radius, are mounted on each segment.

FIGS. 8 and 9 FIGS. 8 and 9 show one of the chipping teeth 68 on the segment 64. The chipping tooth 68 has a thick shank portion 69 of trapezoidal cross-section which has a snug fit in a re-entrant angled recess 71, in the segment 64, and which is held in place by a set screw 72. A thin shank portion 71.1 extends radially outwards beyond the periphery of the segment 64 and carries a chisel shaped insert 73, suitably tungsten carbide, which has a transverse cutting edge 74 and parallel side cutting edges 75 and 76 the edges 75 and 76 extending clear of side surfaces of the portion 71.1 of the shank. Shape of the insert results in production of chips rather than sawdust and a kerf having walls resembling those produced by a conventional circular saw.

Relationship of the chipping teeth and the chipping knives of head assembly 60 is the same as the relationship of the saw teeth and the chipping knives of head assembly 16 and 17 so that the cut, line 63.1 FIG. 9 taken by a chipping knife is clear of the kerf bottom cut by a chipping tooth immediately preceding a knife so as to leave a lip 81. The cut face of the slab immediately prior to a chipping knife cut is shown by the line 63.2 distance between lines 63.1 and 63.2 being maximum chip thickness.

Chipping tooth width and number of chipping teeth per chipping knife is determined in accordance with minimum and maximum permissible dimensional standards for wood chips used in pulping. Typically wood chips are screened to separate undersized and oversized chips from acceptable commonly, chips passing a screen having one and one-quarter inch openings and retained on a screen having three-eighths inch openings are considered acceptable for pulping. Consequently, chipping inserts having a width of, or slightly in excess of, three-eights inch result in the production of chips of acceptable width. Similarly, with the rotational speed of the head and feed rate of the log adjusted so that the chipping knives produce chips having a maximum length of one and one-quarter inches, ratio of three chipping teeth per chipping knife result in production of chips, by the chipping teeth, which meet minimum standard of length. Chipping tooth width and ratio of chipping teeth per chipping knife can, of course, be varied to suit varied dimensional standards.

The chipping head assembly 60 obtains substantialy maximum wood utilization as production of sawdust is, in effect, eliminated. Further, cutting action of the chipping teeth inserts results in provision of a flat planar side surface on a log which closely resembles a surface produced by a conventional circular saw rather than a surface provided by a conventional chipping knife.

I claim:

1. A sawing and chipping machine including:

a. means for feeding a log lengthwise through the machine,

b. a driven head member rotatable about an axis perpendicular to the log, the head member having an inner face,

c. a circular saw mounted on the inner face of the head member having teeth projecting outward of a periphery of the head for cutting a slab from the log as the log is fed through the machine,

d. chipping knives mounted on the head member for progressively reducing the slab to chips as it is being cut from the log by the saw, the chipping knives being disposed so that their cutting edges project into the kerf cut by the saw and terminate short of the saw face confronting the log and extend outwards beyond the periphery of the head member so as to provide a chipped end face on the slab clear of the periphery of the member.

2. A sawing and chipping machine as claimed in claim 1 in which the radius of each chipping knife is less than the radius ofa saw tooth immediately preceding a distance such that a kerf bottom cut by the saw teeth precedes the chipped end face of the slab.

3. A sawing and chipping machine as claimed in claim 1 in which the saw has a tooth gap at each chipping knife greater in extent than one saw tooth and radius of the saw teeth increases uniformly and incrementally from the tooth immediately following a chipping knife to the tooth immediately preceding the next chipping knife so that extra cutting load occasioned by the tooth gap is distributed equally to each tooth.

4. A sawing and chipping machine as claimed in claim 1 in which the circular saw is segmented, having a segment extending between adjacent chipping knives, each segment being circumferentially spaced from an adjacent segment so as to present a tooth gap greater in extent than one tooth, each segment having a center of curvature offset eccentrically from the axis of rotation of the head a distance such that radius of the saw teeth of each segment increases incrementally from the lead tooth to the trailing tooth so that extra cutting load occasioned by the toothgap is distributed equally to the teeth of each segment.

5. A sawing and chipping machine as claimed in claim 1 in which each saw tooth is chisel shaped having a transverse cutting edge and parallel side cutting edges for reducing kerf wood to chips.

6. A sawing and chipping machine as claimed in claim 1 in which the saw has a gullet between adjacent teeth, each gullet having a length in excess of maximum kerf depth so that the gullet bottoms open clear of the chipped end face of the slab, the gullet bottoms being outwardly bevelled so that wood cut by the saw is directed laterally outwards from the sawn surface of the log.

7. A sawing and chipping machine as claimed in claim 1 in which the saw has a substantially thick radial inner portion from which the saw teeth, thinner than said inner portion, radially project, the saw teeth and radial inner portion having inner log confronting faces extending in a common plane. 

1. A sawing and chipping machine including: a. means for feeding A log lengthwise through the machine, b. a driven head member rotatable about an axis perpendicular to the log, the head member having an inner face, c. a circular saw mounted on the inner face of the head member having teeth projecting outward of a periphery of the head for cutting a slab from the log as the log is fed through the machine, d. chipping knives mounted on the head member for progressively reducing the slab to chips as it is being cut from the log by the saw, the chipping knives being disposed so that their cutting edges project into the kerf cut by the saw and terminate short of the saw face confronting the log and extend outwards beyond the periphery of the head member so as to provide a chipped end face on the slab clear of the periphery of the member.
 2. A sawing and chipping machine as claimed in claim 1 in which the radius of each chipping knife is less than the radius of a saw tooth immediately preceding a distance such that a kerf bottom cut by the saw teeth precedes the chipped end face of the slab.
 3. A sawing and chipping machine as claimed in claim 1 in which the saw has a tooth gap at each chipping knife greater in extent than one saw tooth and radius of the saw teeth increases uniformly and incrementally from the tooth immediately following a chipping knife to the tooth immediately preceding the next chipping knife so that extra cutting load occasioned by the tooth gap is distributed equally to each tooth.
 4. A sawing and chipping machine as claimed in claim 1 in which the circular saw is segmented, having a segment extending between adjacent chipping knives, each segment being circumferentially spaced from an adjacent segment so as to present a tooth gap greater in extent than one tooth, each segment having a center of curvature offset eccentrically from the axis of rotation of the head a distance such that radius of the saw teeth of each segment increases incrementally from the lead tooth to the trailing tooth so that extra cutting load occasioned by the tooth gap is distributed equally to the teeth of each segment.
 5. A sawing and chipping machine as claimed in claim 1 in which each saw tooth is chisel shaped having a transverse cutting edge and parallel side cutting edges for reducing kerf wood to chips.
 6. A sawing and chipping machine as claimed in claim 1 in which the saw has a gullet between adjacent teeth, each gullet having a length in excess of maximum kerf depth so that the gullet bottoms open clear of the chipped end face of the slab, the gullet bottoms being outwardly bevelled so that wood cut by the saw is directed laterally outwards from the sawn surface of the log.
 7. A sawing and chipping machine as claimed in claim 1 in which the saw has a substantially thick radial inner portion from which the saw teeth, thinner than said inner portion, radially project, the saw teeth and radial inner portion having inner log confronting faces extending in a common plane. 